His research and work ranges from the philosophy of measurement, through model developments, exposition and interpretation, to software development. He has published in Educational, Psychological, Sociological and Statistical journals. He is the author of Rasch Models for Measurement (Sage) and coauthor of the software package Rasch Unidimensional Measurement Models (RUMMLab). He has published extensively in areas ranging from Rasch models to philosophy of science. Some of these publications are listed in articles on the Rasch model and polytomous Rasch model.